Pregnancy Attrition Associated with Pregnancy Testing by Rectal Palpation

¹ Texas Veterinary Medical Center, Texas A&M University, College Station 77843
² Department of Clinical and Population Sciences, University of Minnesota, St. Paul 55108
³ Department of Statistics, Texas A&M University, College Station 77843
⁴ Department of Population Medicine, University of Guelph, Guelph, ON, Canada N1G 2W1
⁵ Department of Medical Sciences, University of Wisconsin, Madison 53706

The objective of this study was to estimate the effect on calving risk of interval from AI date until scheduled date of pregnancy examination. First AI (n = 7105) from 65 dairy herds in the United States and Canada were followed for 294 d to determine whether cows calved. Calving was modeled as a function of the number of days in the interval, herd, season, and breeding at PGF₂-induced estrus by multivariate logistic regression. The main effects of herd and AI following PGF₂-induced estrus were significantly associated with calving rate from first AI. The main effects of interval and season were not significantly associated with calving. The effects of PGF₂, season, and interval between AI and pregnancy testing varied significantly among herds. These effects appear to be symmetric in their distributions about their means. The risk of day of palpation on calving is herd dependent and small compared with other herd factors.

Key Words: pregnancy attrition • rectal palpation • herd

Submitted on March 17, 1994
Accepted on May 23, 1994